Assessment of Mercury Detoxification Potentiality of Isolated Streptococcus sp. MTCC 9724 under Different Environmental Conditions

The objectives of the present study were to isolate and identify a suitable mercury resistance bacterial strain and to explore their detoxification potentiality of mercury in different environmental conditions. A strain of Streptococcus sp. MTCC 9724 was isolated from the soil of waste dumping site adjacent to East Calcutta wetlands, West Bengal, India. Minimum inhibitory concentration of mercury was estimated. The bacteria were resistant to lead, arsenic, chromium and copper and antibiotics like Tetracycline, Ofloxacin, Amoxicillin, Ampicillin, Chloramphenicol and Cefadroxil. The bacteria were exposed containing 2, 5 and 10 mg/l of mercury containing media with variable pH, phenol and chloride ions as co-pollutants. It was observed that acidic pH was not suitable for bacterial growth and also for mercury detoxification. The presence of phenol in wastewater actually supported bacterial population growth and also mercury removal within 16 hours time periods, which indicated that utilization of phenol as a sole carbon source for bacterial metabolism, where as chloride ions up to 21 g/l did not inhibit the bacterial growth but significantly decreased the detoxification potentiality of Streptococcus sp. MTCC 9724.